1. Field of the Invention
The subject invention is directed to a bearing hanger assembly for rotating shaft components, and more particularly, to a bearing hanger assembly for use in aircraft, marine and industrial drive systems to couple a driving shaft and a driven shaft in a manner that accommodates misalignment of the shaft components relative to a supporting structure.
2. Description of Related Art
Bearing hangers for coupling two shafts such as a driving shaft and a driven shaft, which transmit torque while accommodating axial and/or angular misalignment of the shafts relative to a supporting structure have long been used in aircraft, marine and industrial applications. Many of these prior art devices have employed elastomeric, visco-elastic and/or spherical bearing elements to accommodate shaft extension and misalignment. Other prior art coupling devices have used one or more contoured diaphragms to accommodate shaft extension and misalignment. For example, U.S. Pat. No. 5,158,504 to Stocco describes a device that uses contoured diaphragms welded together to form a flexible coupling between a driving shaft and a driven shaft.
In the past, prior art coupling diaphragms have been designed with torque transmission as a primary design consideration and flexibility as a secondary design consideration. However, there are applications in which torque transmission requirements are more easily achieved and the flexibility requirement becomes the prime design factor, such as in aircraft and industrial drive systems. Typically, in such instances, the flexibility feature of the diaphragm is incorporated in its cross-sectional profile, as disclosed for example in U.S. Pat. No. 5,158,504 to Stocco.
It is known in the art that that the torque transmitting capacity of a flexible diaphragm varies as the reciprocal of the square of its radius. For that reason, in prior art devices, the thinnest section of the diaphragm has been nearest to the outer periphery thereof. However, this generates high stresses in the outer peripheral area under axial deflection or bending conditions resulting from angularly misaligned shafts.
The subject invention provides a bearing hanger that employs a flexible diaphragm with a profile that enables the diaphragm to accommodate axial deflections without over-stressing the diaphragm material. In order to accommodate this condition the diaphragm is thinnest in areas where the diaphragm stress will be low. Furthermore, the profile of the diaphragm takes into account the torque transmission requirements and the buckling stability of the coupling.
In the subject invention, the diaphragm profile is preferably optimized so that the bending moment developed by axial and angular deflections is small at the thinnest section of the contoured profile. This ensures that stress levels are minimal throughout the diaphragm. Consequently, greater axial deflection and bending can be accommodated before the diaphragm material reaches its endurance limit.